0001564590-20-052747 | 10-Q | XBRL Viewer

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Document and Entity Information - shares	9 Months Ended
Document and Entity Information - shares	Sep. 30, 2020	Nov. 10, 2020
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2020
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q3
Trading Symbol	PRLD
Entity Registrant Name	Prelude Therapeutics Inc
Entity Central Index Key	0001678660
Entity Current Reporting Status	Yes
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Common Stock, Shares Outstanding		43,703,381
Entity Shell Company	false
Title of 12(b) Security	Common Stock, par value $0.0001 per share
Security Exchange Name	NASDAQ
Entity Interactive Data Current	Yes
Entity File Number	001-39527
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	81-1384762
Entity Address, Address Line One	200 Powder Mill Road
Entity Address, City or Town	Wilmington
Entity Address, State or Province	DE
Entity Address, Postal Zip Code	19803
City Area Code	302
Local Phone Number	467-1280
Document Quarterly Report	true
Document Transition Report	false

STATEMENT OF BALANCE SHEETS (UNAUDITED) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 234,792	$ 18,879
Prepaid expenses and other current assets	3,269	1,345
Total current assets	238,061	20,224
Property and equipment, net	1,620	1,647
Total assets	239,681	21,871
Current liabilities:
Capital lease obligation		258
Accounts payable	5,074	1,974
Accrued expenses and other current liabilities	6,285	2,603
Total current liabilities	11,359	4,835
Other liabilities	15	5
Total liabilities	11,374	4,840
Total convertible preferred stock		66,443
Commitments
Stockholders’ equity (deficit):
Additional paid-in capital	316,479	1,085
Accumulated deficit	(88,176)	(50,497)
Total stockholders’ equity (deficit)	228,307	(49,412)
Total liabilities, convertible preferred stock and stockholders’ equity (deficit)	239,681	21,871
Series A Convertible Preferred Stock
Current liabilities:
Total convertible preferred stock		36,595
Series B Convertible Preferred Stock
Current liabilities:
Total convertible preferred stock		$ 29,848
Voting Common Stock
Stockholders’ equity (deficit):
Common stock	3
Total stockholders’ equity (deficit)	3
Non-voting Common Stock
Stockholders’ equity (deficit):
Common stock	1
Total stockholders’ equity (deficit)	$ 1

STATEMENT OF BALANCE SHEETS (PARENTHETICAL) (UNAUDITED) - $ / shares	Sep. 30, 2020	Dec. 31, 2019
Convertible preferred stock, par value	$ 0.0001	$ 0.0001
Convertible preferred stock, shares outstanding	0
Common stock, par value	$ 0.0001
Common stock, shares authorized	500,000,000
Series A Convertible Preferred Stock
Convertible preferred stock, shares authorized	0	13,574,008
Convertible preferred stock, shares issued	0	11,736,119
Convertible preferred stock, shares outstanding	0	11,736,119
Series B Convertible Preferred Stock
Convertible preferred stock, shares authorized	0	18,500,000
Convertible preferred stock, shares issued	0	7,628,846
Convertible preferred stock, shares outstanding	0	7,628,846
Series C Convertible Preferred Stock
Convertible preferred stock, shares authorized	0	0
Convertible preferred stock, shares issued	0	0
Convertible preferred stock, shares outstanding	0	0
Voting Common Stock
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	487,149,741	42,000,000
Common stock, shares, issued	32,593,010	3,161,653
Common stock, shares, outstanding	32,593,010	3,161,653
Non-voting Common Stock
Common stock, par value	$ 0.0001	$ 0.0001
Common stock, shares authorized	12,850,259	0
Common stock, shares, issued	11,110,371	0
Common stock, shares, outstanding	11,110,371	0

STATEMENTS OF OPERATIONS (UNAUDITED) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Operating expenses:
Research and development	$ 15,293	$ 5,490	$ 33,605	$ 15,430
General and administrative	2,851	1,394	5,712	2,584
Total operating expenses	18,144	6,884	39,317	18,014
Loss from operations	(18,144)	(6,884)	(39,317)	(18,014)
Other income, net	1,384	150	1,638	483
Net loss	$ (16,760)	$ (6,734)	$ (37,679)	$ (17,531)
Per share information:
Net loss per share of common stock, basic and diluted	$ (5.25)	$ (3.93)	$ (15.83)	$ (10.80)
Weighted average common shares outstanding, basic and diluted	3,194,471	1,713,371	2,380,100	1,622,546

STATEMENTS OF CHANGES IN CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS' EQUITY (DEFICIT) (UNAUDITED) - USD ($) $ in Thousands	Total	Series A Convertible Preferred Stock	Series B Convertible Preferred Stock	Series C Convertible Preferred Stock	Non-voting Common Stock	Voting Common Stock	Additional Paid-in Capital	Accumulated Deficit	Common Stock
Convertible preferred stock, Beginning balance at Dec. 31, 2018		$ 36,595
Convertible preferred stock, Beginning balance (shares) at Dec. 31, 2018		11,736,119
Beginning balance at Dec. 31, 2018	$ (22,693)						$ 234	$ (22,927)
Beginning balance (shares) at Dec. 31, 2018									2,380,270
Stock-based compensation expense, including issuance of restricted stock awards	82						82
Net loss	(5,241)							(5,241)
Convertible preferred stock, Ending balance at Mar. 31, 2019		$ 36,595
Convertible preferred stock, Ending balance (shares) at Mar. 31, 2019		11,736,119							2,380,270
Ending balance at Mar. 31, 2019	(27,852)						316	(28,168)
Convertible preferred stock, Beginning balance at Dec. 31, 2018		$ 36,595
Convertible preferred stock, Beginning balance (shares) at Dec. 31, 2018		11,736,119
Beginning balance at Dec. 31, 2018	(22,693)						234	(22,927)
Beginning balance (shares) at Dec. 31, 2018									2,380,270
Net loss	(17,531)
Convertible preferred stock, Ending balance at Sep. 30, 2019		$ 36,595	$ 29,848
Convertible preferred stock, Ending balance (shares) at Sep. 30, 2019		11,736,119	7,628,846
Ending balance at Sep. 30, 2019	(39,699)						759	(40,458)
Ending balance (shares) at Sep. 30, 2019									3,161,653
Convertible preferred stock, Beginning balance at Mar. 31, 2019		$ 36,595
Convertible preferred stock, Beginning balance (shares) at Mar. 31, 2019		11,736,119							2,380,270
Beginning balance at Mar. 31, 2019	(27,852)						316	(28,168)
Sale of convertible preferred stock, net of issuance costs			$ 29,848
Sale of convertible preferred stock, net of issuance costs (shares)			7,628,846
Exercise of stock options	5						5
Exercise of stock options (shares)									3,242
Stock-based compensation expense, including issuance of restricted stock awards	141						141
Stock-based compensation expense, including issuance of restricted stock awards (shares)									345,840
Net loss	(5,556)							(5,556)
Convertible preferred stock, Ending balance at Jun. 30, 2019		$ 36,595	$ 29,848
Convertible preferred stock, Ending balance (shares) at Jun. 30, 2019		11,736,119	7,628,846
Ending balance at Jun. 30, 2019	(33,262)						462	(33,724)
Ending balance (shares) at Jun. 30, 2019									2,729,352
Stock-based compensation expense, including issuance of restricted stock awards	297						297
Stock-based compensation expense, including issuance of restricted stock awards (shares)									432,301
Net loss	(6,734)							(6,734)
Convertible preferred stock, Ending balance at Sep. 30, 2019		$ 36,595	$ 29,848
Convertible preferred stock, Ending balance (shares) at Sep. 30, 2019		11,736,119	7,628,846
Ending balance at Sep. 30, 2019	(39,699)						759	(40,458)
Ending balance (shares) at Sep. 30, 2019									3,161,653
Convertible preferred stock, Beginning balance at Dec. 31, 2019	66,443	$ 36,595	$ 29,848
Convertible preferred stock, Beginning balance (shares) at Dec. 31, 2019		11,736,119	7,628,846	0
Beginning balance at Dec. 31, 2019	(49,412)						1,085	(50,497)
Beginning balance (shares) at Dec. 31, 2019						3,161,653
Sale of convertible preferred stock, net of issuance costs			$ 29,942
Sale of convertible preferred stock, net of issuance costs (shares)			7,628,846
Stock-based compensation expense, including issuance of restricted stock awards	362						362
Stock-based compensation expense, including issuance of restricted stock awards (shares)						432,301
Net loss	(9,511)							(9,511)
Convertible preferred stock, Ending balance at Mar. 31, 2020		$ 36,595	$ 59,790
Convertible preferred stock, Ending balance (shares) at Mar. 31, 2020		11,736,119	15,257,692
Ending balance at Mar. 31, 2020	(58,561)						1,447	(60,008)
Ending balance (shares) at Mar. 31, 2020						3,593,954
Convertible preferred stock, Beginning balance at Dec. 31, 2019	66,443	$ 36,595	$ 29,848
Convertible preferred stock, Beginning balance (shares) at Dec. 31, 2019		11,736,119	7,628,846	0
Beginning balance at Dec. 31, 2019	$ (49,412)						1,085	(50,497)
Beginning balance (shares) at Dec. 31, 2019						3,161,653
Exercise of stock options (shares)	98,254
Net loss	$ (37,679)
Convertible preferred stock, Ending balance (shares) at Sep. 30, 2020	0	0	0	0
Ending balance at Sep. 30, 2020	$ 228,307				$ 1	$ 3	316,479	(88,176)
Ending balance (shares) at Sep. 30, 2020					11,110,371	32,593,010
Convertible preferred stock, Beginning balance at Mar. 31, 2020		$ 36,595	$ 59,790
Convertible preferred stock, Beginning balance (shares) at Mar. 31, 2020		11,736,119	15,257,692
Beginning balance at Mar. 31, 2020	(58,561)						1,447	(60,008)
Beginning balance (shares) at Mar. 31, 2020						3,593,954
Exercise of stock options	31						31
Exercise of stock options (shares)						36,745
Stock-based compensation expense, including issuance of restricted stock awards	627						627
Net loss	(11,408)							(11,408)
Convertible preferred stock, Ending balance at Jun. 30, 2020		$ 36,595	$ 59,790
Convertible preferred stock, Ending balance (shares) at Jun. 30, 2020		11,736,119	15,257,692
Ending balance at Jun. 30, 2020	(69,311)						2,105	(71,416)
Ending balance (shares) at Jun. 30, 2020						3,630,699
Sale of convertible preferred stock, net of issuance costs				$ 49,826
Sale of convertible preferred stock, net of issuance costs (shares)				3,443,612
Exercise of stock options	65						65
Exercise of stock options (shares)						61,509
Conversion of convertible preferred stock into voting and non-voting common stock upon initial public offering	146,211				$ 1	$ 2	146,208
Conversion of convertible preferred stock into common stock upon initial public offering (shares)		(11,736,119)	(15,257,692)	(3,443,612)
Conversion of convertible preferred stock into common stock upon initial public offering		$ (36,595)	$ (59,790)	$ (49,826)
Conversion of convertible preferred stock into common stock upon initial public offering (shares)					11,110,371	19,327,052
Sale of common stock in initial public offering, net of offering costs of $2,538	166,630					$ 1	166,629
Sale of common stock in initial public offering, net of offering costs of $2,538, (shares)						9,573,750
Stock-based compensation expense, including issuance of restricted stock awards	1,472						1,472
Net loss	$ (16,760)							(16,760)
Convertible preferred stock, Ending balance (shares) at Sep. 30, 2020	0	0	0	0
Ending balance at Sep. 30, 2020	$ 228,307				$ 1	$ 3	$ 316,479	$ (88,176)
Ending balance (shares) at Sep. 30, 2020					11,110,371	32,593,010

STATEMENTS OF CHANGES IN CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS' EQUITY (DEFICIT) (PARENTHETICAL) (UNAUDITED) - USD ($) $ in Thousands	3 Months Ended
	Sep. 30, 2020	Mar. 31, 2020	Jun. 30, 2019
Sale of common stock, offering costs	$ 2,538
Series B Convertible Preferred Stock
Sale of convertible preferred stock, issuance costs		$ 58	$ 152
Series C Convertible Preferred Stock
Sale of convertible preferred stock, issuance costs	$ 174

STATEMENTS OF CASH FLOWS (UNAUDITED) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Cash flows used in operating activities:
Net loss	$ (37,679)	$ (17,531)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	409	254
Stock-based compensation	2,461	520
Changes in operating assets and liabilities:
Prepaid expenses and other current assets	(1,924)	(344)
Accounts payable	1,931	(76)
Accrued expenses and other liabilities	3,472	(19)
Net cash used in operating activities	(31,330)	(17,196)
Cash flows used in investing activities:
Purchases of property and equipment	(292)	(581)
Net cash used in investing activities	(292)	(581)
Cash flows provided by financing activities:
Proceeds from the issuance of common stock upon initial public offering, net of offering costs	167,929
Payment of capital lease obligation	(258)	(31)
Proceeds from the exercise of stock options	96	5
Net cash provided by financing activities	247,535	29,822
Net increase in cash and cash equivalents	215,913	12,045
Cash and cash equivalents at beginning of period	18,879	15,595
Cash and cash equivalents at end of period	234,792	27,640
Supplemental disclosures:
Property and equipment in accounts payable	90	108
Offering costs in accrued expenses and other current liabilities	220
Offering costs in accounts payable	1,079
Series C Convertible Preferred Stock
Cash flows provided by financing activities:
Proceeds from the sale of convertible preferred stock, net of offering costs	49,826
Series B Convertible Preferred Stock
Cash flows provided by financing activities:
Proceeds from the sale of convertible preferred stock, net of offering costs	$ 29,942	$ 29,848

Background

9 Months Ended

Sep. 30, 2020

Background [Abstract]

Background

1. Background

Prelude Therapeutics Incorporated (the “Company”) was incorporated in Delaware on February 5, 2016 and is a clinical-stage precision oncology company focused on discovering and developing small molecule therapies optimized to target the key driver mechanisms in cancers with high unmet need. Since beginning operations, the Company has devoted substantially all its efforts to research and development, conducting preclinical and clinical studies, recruiting management and technical staff, administration, and raising capital.

In September 2020, the Company closed its initial public offering (“IPO”) in which the Company issued and sold 9,573,750 shares of its common stock at a public offering price of $19.00 per share for net proceeds of $166.6 million after deducting underwriting discounts, commissions and other offering expenses paid or to be paid. Subsequent to the closing of the IPO, there were no shares of convertible preferred stock outstanding. In connection with the closing of the IPO, the Company amended and restated its Fifth Amended and Restated Certificate of Incorporation to change the authorized capital stock to 500,000,000 shares designated as common stock (of which 12,850,259 shares are non-voting common stock) and 10,000,000 shares designated as preferred stock, all with a par value of $0.0001 per share.

Risks and Liquidity

9 Months Ended

Sep. 30, 2020

Risks And Liquidity [Abstract]

Risks and Liquidity

2. Risks and liquidity

The Company is subject to a number of risks common to early-stage companies in the biotechnology industry. Principal among these risks are the uncertainties in the development process, development of the same or similar technological innovations by competitors, protection of proprietary technology, dependence on key personnel, compliance with government regulations and approval requirements, and the need to obtain additional financing to fund operations. Product candidates currently under development will require significant additional research and development efforts, including extensive pre-clinical and clinical testing and regulatory approval, prior to commercialization. These efforts require significant amounts of additional capital, adequate personnel infrastructure, and extensive compliance-reporting capabilities. There can be no assurance that the Company’s research and development will be successfully completed, that adequate protection for the Company’s technology will be obtained, that any products developed will obtain necessary government regulatory approval, or that any approved products will be commercially viable. The Company operates in an environment of rapid change in technology and substantial competition from pharmaceutical and biotechnology companies. In addition, the Company is dependent upon the services of its employees, consultants and contractors.

Since its inception, the Company has incurred operating losses and has an accumulated deficit of $88.2 million at September 30, 2020. The Company has no revenue to date and devotes its efforts to research and development. The Company anticipates incurring additional losses until such time, if ever, that it can generate significant sales of its product candidates currently in development.

The Company believes that its cash and cash equivalents as of September 30, 2020, which includes the net proceeds of approximately $166.6 million from the IPO of the Company’s common stock completed in September 2020, will be sufficient to fund its operating expenses and capital expenditure requirements into the second half of 2022.

To fund its operating expenses and capital expenditure requirements after that date, the Company plans to seek additional funding through public or private equity offerings, debt financings, collaborations, strategic alliances and licensing arrangements. The Company may not be able to obtain financing on acceptable terms, or at all, and the Company may not be able to enter into strategic alliances or other arrangements on favorable terms, or at all. The terms of any financing may adversely affect the holdings or the rights of the Company’s stockholders. If the Company is unable to obtain funding, the Company could be required to delay, reduce or eliminate research and development programs, product portfolio expansion or future commercialization efforts, which could adversely affect its business prospects.

On March 10, 2020, the World Health Organization characterized the novel COVID-19 virus as a global pandemic. There is significant uncertainty as to the likely effects of this disease which may, among other things, materially impact the Company’s planned clinical trials. This pandemic or outbreak could result in difficulty securing clinical trial site locations, CROs, and/or trial monitors and other critical vendors and consultants supporting the trial. In addition, outbreaks or the perception of an outbreak near a clinical trial site location could impact the Company’s ability to enroll patients. These situations, or others associated with COVID-19, could cause delays in the Company’s clinical trial plans and could increase expected costs, all of which could have a material adverse effect on the Company’s business and its financial condition. At the current time, the Company is unable to quantify the potential effects of this pandemic on its future financial statements.

Summary of Significant Accounting Policies

9 Months Ended

Sep. 30, 2020

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

3. Summary of significant accounting policies

The summary of significant accounting policies included in the Company’s financial statements for the year ended December 31, 2019 can be found in “Note 3. Summary of significant accounting policies” of the Company’s prospectus filed with the Securities and Exchange Commission (the “SEC”) on September 25, 2020 (the “Prospectus”). Those policies have not materially changed, except as set forth below.

Basis of presentation

The accompanying unaudited interim financial statements have been prepared in accordance with generally accepted accounting principles (“GAAP”) for interim financial information, the instructions to Form 10-Q and Article 10 of Regulation S-X. They do not include all of the information and notes required by GAAP for complete financial statements. In the opinion of management, all adjustments (consisting of normal recurring accruals) considered necessary for a fair presentation have been included. Operating results for the three and nine month periods ended September 30, 2020 are not necessarily indicative of the results that may be expected for the year ended December 31, 2020. The accompanying unaudited interim financial statements should be read in conjunction with the annual audited financial statements and related notes as of and for the year ended December 31, 2019 found in the Prospectus filed with the SEC on September 25, 2020. Any reference in these notes to applicable guidance is meant to refer to GAAP as found in the Accounting Standards Codification (“ASC”) and Accounting Standards Updates (“ASU”) of the Financial Accounting Standards Board (“FASB”).

On September 18, 2020, the Company’s board of directors and stockholders approved a 1.1566-to-one reverse stock split of the Company’s issued and outstanding shares of common stock and convertible preferred stock. All share and per share amounts in the unaudited interim financial statements and notes hereto have been retrospectively adjusted for all periods presented to give effect to the reverse stock split.

The completion of the IPO, as described above, impacts the comparability of certain amounts to the corresponding prior year period, including earnings per share.

Use of estimates

The preparation of the unaudited interim financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and contingent liabilities at the date of the unaudited interim financial statements and the reported amounts of expenses during the reporting period. Actual results could differ from those estimates.

Estimates and assumptions are periodically reviewed and the effects of the revisions are reflected in the accompanying unaudited interim financial statements in the period they are determined to be necessary. Prior to the IPO, significant areas that required management’s estimates included the fair value of the Company’s common stock, stock-based compensation assumptions and accrued clinical trial expenses. Subsequent to the IPO, the most significant estimate relates to accrued clinical trial expenses.

Income taxes

Based upon the historical and anticipated future losses, management has determined that the deferred tax assets generated by net operating losses and research and development credits do not meet the more likely than not threshold for realizability. Accordingly, a full valuation allowance has been recorded against the Company’s net deferred tax assets as of September 30, 2020 and December 31, 2019.

Net Loss Per Share

Basic net loss per share of common stock is computed by dividing net loss by the weighted-average number of shares of common stock outstanding during each period. The weighted-average number of shares of common stock outstanding used in the basic net loss per share calculation does not include unvested restricted stock awards as these instruments are considered contingently issuable shares until they vest. Diluted net loss per share of common stock includes the effect, if any, from the potential exercise or conversion of securities, such as convertible preferred stock and stock options, which would result in the issuance of incremental shares of common stock. For diluted net loss per share, the weighted-average number of shares of common stock is the same for basic net loss per share due to the fact that when a net loss exists, dilutive securities are not included in the calculation as the impact is anti-dilutive. The Company’s convertible preferred stock and unvested restricted stock entitles the holder to participate in dividends and earnings of the Company, and, if the Company were to recognize net income, it would have to use the two-class method to calculate earnings per share. The two-class method is not applicable during periods with a net loss, as the holders of the convertible preferred stock and unvested restricted stock have no obligation to fund losses.

The following potentially dilutive securities have been excluded from the computation of diluted weighted-average shares of common stock outstanding, as they would be anti-dilutive:

	September 30,
	2020		2019
Series A convertible preferred stock		—		11,736,119
Series B convertible preferred stock		—		7,628,846
Unvested restricted stock awards		1,312,024		1,394,056
Stock options		6,649,882		2,189,333
		7,961,906		22,948,354

Amounts in the above table reflect the common stock equivalents.

Recently Issued Accounting Pronouncements

Emerging Growth Company Status

The Company is an emerging growth company, as defined in the Jumpstart Our Business Startups Act of 2012 (the “JOBS Act”). Under the JOBS Act, emerging growth companies can delay adopting new or revised accounting standards issued subsequent to the enactment of the JOBS Act, until such time as those standards apply to private companies. The Company has elected to use this extended transition period for complying with new or revised accounting standards that have different effective dates for public and private companies until the earlier of the date that it (i) is no longer an emerging growth company or (ii) affirmatively and irrevocably opts out of the extended transition period provided in the JOBS Act. As a result, these unaudited interim financial statements may not be comparable to companies that comply with the new or revised accounting pronouncements as of public company effective dates.

Recent Accounting Pronouncements

In February 2016, the FASB issued ASU No. 2016-02, Leases, which requires a lessee to record a right-of-use asset and a corresponding lease liability on the balance sheet for all leases with terms longer than 12 months. A modified retrospective transition approach is required for lessees for capital and operating leases existing at, or entered into after, the beginning of the earliest comparative period presented in the financial statements, with certain practical expedients available. The standard is effective for the Company beginning January 1, 2022, with early adoption permitted. The Company is currently evaluating the expected impact that the standard will have on its financial statements and related disclosures.

In August 2018, the FASB issued ASU 2018-13, Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurements, which changes the fair value measurement disclosure requirements of ASC Topic 820, Fair Value Measurement (“ASC 820”). The goal of the ASU is to improve the effectiveness of ASC 820’s disclosure requirements. The standard is effective for fiscal years beginning after December 15, 2019 and interim periods therein. The adoption of this standard on January 1, 2020 did not have a material impact on the Company’s unaudited interim financial statements.

Fair Value of Financial Instruments

9 Months Ended

Sep. 30, 2020

Fair Value Disclosures [Abstract]

Fair Value of Financial Instruments

4. Fair Value of Financial Instruments

Fair value is the price that could be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. Fair value determination in accordance with applicable accounting guidance requires that a number of significant judgments be made. Additionally, fair value is used on a nonrecurring basis to evaluate assets for impairment or as required for disclosure purposes by applicable accounting guidance on disclosures about fair value of financial instruments. Depending on the nature of the assets and liabilities, various valuation techniques and assumptions are used when estimating fair value. The Company follows the provisions of ASC 820, for financial assets and liabilities measured on a recurring basis. The guidance requires fair value measurements be classified and disclosed in one of the following three categories:

•

Level 1: Unadjusted quoted prices in active markets that are accessible at the measurement date for identical, unrestricted assets or liabilities.

•

Level 2: Quoted prices in markets that are not active, or inputs which are observable, either directly or indirectly, for substantially the full term of the asset or liabilities.

•

Level 3: Prices or valuation techniques that require inputs that are both significant to the fair value measurement and unobservable (i.e., supported by little or no market activity).

The following fair value hierarchy table presents information about the Company’s assets and liabilities measured at fair value on a recurring basis:

	Fair value measurement at reporting date using
(in thousands)	Quoted prices in active markets for identical assets (Level 1)		Significant other observable inputs (Level 2)		Significant unobservable inputs (Level 3)
September 30, 2020:
Assets:
Cash equivalents (Money Market Funds)	$	233,364	$	—	$	—
December 31, 2019:
Assets:
Cash equivalents (Money Market Funds)	$	18,779	$	—	$	—

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Accrued Expenses and Other Current Liabilities

9 Months Ended

Sep. 30, 2020

Payables And Accruals [Abstract]

Accrued Expenses and Other Current Liabilities

5. Accrued Expenses and Other Current Liabilities

Accrued expenses and other current liabilities consisted of the following:

(in thousands)	September 30, 2020		December 31, 2019
Compensation and related benefits	$	2,099	$	1,631
Research and development		3,763		658
Offering costs		220		—
Professional services and other		203		314
	$	6,285	$	2,603

Convertible Preferred Stock and Common Stock

9 Months Ended

Sep. 30, 2020

Equity [Abstract]

Convertible Preferred Stock and Common Stock

6. Convertible Preferred Stock and Common Stock

Preferred Stock Financings

In August 2020, the Company’s existing Convertible Preferred Stock investors as well as a new investor purchased 3,443,612 shares of Series C at a price of $14.5197 per share for net proceeds of approximately $49.8 million.

In March 2020, the Company’s Series B investors exercised their Future Tranche Right and purchased 7,628,846 shares of Series B for net proceeds of approximately $29.9 million.

Initial Public Offering

In September 2020, the Company completed its IPO in which the Company sold 9,573,750 shares of its common stock at a public offering price of $19.00 per share. The Company received net proceeds of $166.6 million after deducting underwriting discounts, commissions, and other offering expenses paid by the Company. In addition, immediately prior to the closing of the IPO on September 29, 2020, (i) all of the Company’s outstanding shares of convertible preferred stock converted into an aggregate of 30,437,423 shares of common stock (of which, 11,110,371 shares are non-voting common stock) and (ii) the Company filed an amended and restated certificate of incorporation to, among other things, increase the number of authorized shares of common stock to 500,000,000.

Common Stock

The Company has two classes of common stock; “voting common stock” and “non-voting common stock.” The holders of the voting common stock are entitled to one vote for each share of voting common stock held at all meetings of stockholders. Except as otherwise required by law, the holders of non-voting common stock shall not be entitled to vote at any meetings of stockholders (or written actions in lieu of meetings) and the shares of non-voting common stock shall not be included in determining the number of shares voting or entitled to vote on any matter. Unless required by law, there shall be no cumulative voting. Any holder of non-voting common stock may elect to convert each share of non-voting common stock into one fully paid and non-assessable share of voting common stock at any time by providing written notice to the Company; provided that as a result of such conversion, such holder, together with its affiliates and any members of a Schedule 13(d) group with such holder, would not beneficially own in excess of 9.99% of the Company’s common stock immediately prior to and following such conversion, unless otherwise as expressly provided for in the Company’s restated certificate of incorporation. However, this ownership limitation may be increased (not to exceed 19.99%) or decreased to any other percentage designated by such holder of non-voting common stock upon 61 days’ notice to the Company.

Stock-Based Compensation

9 Months Ended

Sep. 30, 2020

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Stock-Based Compensation

7. Stock-Based Compensation

The Company has two equity incentive plans: the 2016 Equity Incentive Plan, as amended, and the 2020 Equity Incentive Plan. New awards can only be granted under the 2020 Equity Incentive Plan (the “Plan”). The total number of shares initially authorized under the Plan was 4,680,000. Of this amount, 4,677,407 shares were available for future grants as of September 30, 2020. The number of shares of the Company’s common stock that may be issued pursuant to rights granted under the Plan shall automatically increase on January 1st of each year, commencing on January 1, 2021 and continuing for ten years, in an amount equal to five percent of the total number of shares of the Company’s common stock outstanding on December 31st of the preceding calendar year, subject to the discretion of the board of directors or compensation committee to determine a lesser number of shares shall be added for such year. The Plan provides for the granting of common stock, incentive stock options, nonqualified stock options, restricted stock awards, and/or stock appreciation rights to employees, directors, and other persons, as determined by the Company’s board of directors. The Company’s stock options vest based on the terms in each award agreement, generally over four-year periods with 25% of options vesting after 1 year and then monthly thereafter, and have a term of ten years. In September 2020, the Company also adopted the 2020 Employee Stock Purchase Plan (the “ESPP”), which includes 520,000 shares of common stock reserved for future issuance. No shares have been issued from the ESPP as of September 30, 2020.

The Company measures stock-based awards at their grant-date fair value and records compensation expense on a straight-line basis over the vesting period of the awards. The Company recorded stock-based compensation expense in the following expense categories in its accompanying statements of operations:

	Three Months Ended September 30,				Nine Months September 30,
(in thousands)	2020		2019		2020		2019
Research and development	$	630	$	135	$	1,047	$	250
General and administrative		842		162		1,414		270
	$	1,472	$	297	$	2,461	$	520

Stock Options

The following table summarizes stock option activity for the periods indicated:

	Number of shares			Weighted average exercise price per share		Weighted average remaining contractual term (years)
Outstanding at January 1, 2020		2,269,742		$	1.66		9.20
Granted		4,594,130		$	9.38
Exercised		(98,254	)	$	0.98
Forfeited		(115,736	)	$	1.37
Outstanding at September 30, 2020		6,649,882		$	7.00		9.40
Exercisable at September 30, 2020		783,236		$	1.64		8.40

At September 30, 2020, the aggregate intrinsic value of outstanding options and exercisable options was $153.7 million and $22.3 million, respectively.

The following table summarizes information about stock options outstanding at September 30, 2020 under the Plan:

	Options Outstanding						Options Exercisable
Range of Exercise Prices	Number Outstanding		Weighted Average Remaining Contractual Life (in years)		Weighted Average Exercise Price		Number Exercisable		Weighted Average Exercise Price
$0.31 - $1.02		253,931		7.43	$	0.98		162,037	$	0.96
$1.43 - $1.89		3,259,095		9.05		1.85		619,998		1.79
$12.85 - $19.00		3,136,856		9.92		12.86		1,201		12.85
		6,649,882						783,236

The weighted-average grant date fair value of options granted was $8.44 and $1.40 per share for the nine months ended September 30, 2020 and 2019, respectively. The aggregate intrinsic value of options exercised was $2.9 million for the nine months ended September 30, 2020. The Company recorded stock-based compensation expense of $1.2 million and $0.2 million for the three months ended September 30, 2020 and 2019, respectively, related to stock options. The Company recorded stock-based compensation expense of $1.9 million and $0.3 million for the nine months ended September 30, 2020 and 2019, respectively, related to stock options. As of September 30, 2020, the total unrecognized compensation expense related to unvested stock option awards was $39.1 million, which the Company expects to recognize over a weighted-average period of 3.74 years.

The fair value of each option was estimated on the date of grant using the weighted average assumptions in the table below:

	Nine months ended September 30,
	2020			2019
Expected volatility		115.09	%		91.60	%
Risk-free interest rate		0.42	%		1.88	%
Expected life (in years)		6.25			6.25
Expected dividend yield		—			—

Restricted Stock Awards

The Company issues restricted stock awards (“RSA”) to employees that generally vest over a four-year period with 25% of awards vesting after one year and then monthly thereafter. Any unvested shares will be forfeited upon termination of services. The fair value of an RSA is equal to the fair market value price of the Company’s common stock on the date of grant. RSA expense is amortized straight-line over the vesting period.

The following table summarizes activity related to RSA stock-based payment awards:

	Number of shares			Weighted-average grant date fair value
Unvested balance at January 1, 2020		1,335,349		$	1.42
Granted		432,301		$	3.26
Vested		(455,626	)	$	1.40
Unvested balance at September 30, 2020		1,312,024		$	2.03

The Company recorded stock-based compensation expense of $0.3 million and $0.1 million for the three months ended September 30, 2020 and 2019, respectively, related to RSAs. The Company recorded stock-based compensation expense of $0.6 million and $0.3 million for the nine months ended September 30, 2020 and 2019, respectively, related to RSAs. As of September 30, 2020, the total unrecognized expense related to all RSAs was $2.4 million, which the Company expects to recognize over a weighted-average period of 2.94 years.

Subsequent Events

9 Months Ended

Sep. 30, 2020

Subsequent Events [Abstract]

Subsequent Events

8. Subsequent Events

On November 1, 2020, the Company entered into a Second Amended and Restated Entrepreneur Client License Agreement (the “Amendment”) with Delaware Innovation Space, Inc. (“DISI”) to amend the Amended and Restated Entrepreneur Client License Agreement dated June 1, 2020 (the “Original Agreement”) relating to the Company’s office and laboratory space in Wilmington, Delaware. The Amendment provides for the expansion of the premises by approximately 8,800 rentable square feet (the “Expansion Space”). Upon inclusion of the Expansion Space, the Company will license approximately 19,800 rentable square feet of office space (the “Premises”) from DISI (the “License”). Pursuant to the Amendment, the initial term of the License is twenty-six months commencing on November 1, 2020 and terminating on December 31, 2022 (the “Initial Term”).

The total base license fee for the Premises through the Initial Term is expected to be $3.0 million (the “License Fee”). The Company has an option to renew the License for twelve months commencing on January 1, 2023 at a monthly renewal license fee increased by 5.0% for a total of $1.4 million payable during the renewal term.

Pursuant to the Amendment, the Company was granted a right of first offer (the “ROFO”) in connection with certain licensable additional space on the Premises that becomes vacant prior to October 31, 2021 (“Available ROFO Space”). If the Company exercises its ROFO, the Company will pay to DISI an increased monthly license fee not to exceed $0.2 million per month at any time during the Initial Term. As consideration for the ROFO, the Company paid DISI a one-time payment of $0.2 million.

Summary of Significant Accounting Policies (Policies)

9 Months Ended

Sep. 30, 2020

Accounting Policies [Abstract]

Basis of presentation

The completion of the IPO, as described above, impacts the comparability of certain amounts to the corresponding prior year period, including earnings per share.

Use of estimates

Income taxes

Net Loss Per Share

The following potentially dilutive securities have been excluded from the computation of diluted weighted-average shares of common stock outstanding, as they would be anti-dilutive:

	September 30,
	2020		2019
Series A convertible preferred stock		—		11,736,119
Series B convertible preferred stock		—		7,628,846
Unvested restricted stock awards		1,312,024		1,394,056
Stock options		6,649,882		2,189,333
		7,961,906		22,948,354

Amounts in the above table reflect the common stock equivalents.

Recently Issued Accounting Pronouncements

Emerging Growth Company Status

Recent Accounting Pronouncements

- Definition

Disclosure of accounting policy for income taxes, which may include its accounting policies for recognizing and measuring deferred tax assets and liabilities and related valuation allowances, recognizing investment tax credits, operating loss carryforwards, tax credit carryforwards, and other carryforwards, methodologies for determining its effective income tax rate and the characterization of interest and penalties in the financial statements.

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Summary of Significant Accounting Policies (Tables)

9 Months Ended

Sep. 30, 2020

Accounting Policies [Abstract]

Schedule of Potentially Dilutive Securities Excluded from Computation of Diluted Weighted-average Shares of Common Stock Outstanding

The following potentially dilutive securities have been excluded from the computation of diluted weighted-average shares of common stock outstanding, as they would be anti-dilutive:

	September 30,
	2020		2019
Series A convertible preferred stock		—		11,736,119
Series B convertible preferred stock		—		7,628,846
Unvested restricted stock awards		1,312,024		1,394,056
Stock options		6,649,882		2,189,333
		7,961,906		22,948,354

Fair Value of Financial Instruments (Tables)

9 Months Ended

Sep. 30, 2020

Fair Value Disclosures [Abstract]

Schedule of Assets and Liabilities Measured at Fair Value on Recurring Basis

The following fair value hierarchy table presents information about the Company’s assets and liabilities measured at fair value on a recurring basis:

	Fair value measurement at reporting date using
(in thousands)	Quoted prices in active markets for identical assets (Level 1)		Significant other observable inputs (Level 2)		Significant unobservable inputs (Level 3)
September 30, 2020:
Assets:
Cash equivalents (Money Market Funds)	$	233,364	$	—	$	—
December 31, 2019:
Assets:
Cash equivalents (Money Market Funds)	$	18,779	$	—	$	—

Accrued Expenses and Other Current Liabilities (Tables)

9 Months Ended

Sep. 30, 2020

Payables And Accruals [Abstract]

Summary of Accrued Expenses and Other Current Liabilities

Accrued expenses and other current liabilities consisted of the following:

(in thousands)	September 30, 2020		December 31, 2019
Compensation and related benefits	$	2,099	$	1,631
Research and development		3,763		658
Offering costs		220		—
Professional services and other		203		314
	$	6,285	$	2,603

Stock-Based Compensation (Tables)

9 Months Ended

Sep. 30, 2020

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Schedule of Stock-Based Compensation Expense Recorded in Statements of Operations

The Company recorded stock-based compensation expense in the following expense categories in its accompanying statements of operations:

	Three Months Ended September 30,				Nine Months September 30,
(in thousands)	2020		2019		2020		2019
Research and development	$	630	$	135	$	1,047	$	250
General and administrative		842		162		1,414		270
	$	1,472	$	297	$	2,461	$	520

Summary of Stock Option Activity

The following table summarizes stock option activity for the periods indicated:

	Number of shares			Weighted average exercise price per share		Weighted average remaining contractual term (years)
Outstanding at January 1, 2020		2,269,742		$	1.66		9.20
Granted		4,594,130		$	9.38
Exercised		(98,254	)	$	0.98
Forfeited		(115,736	)	$	1.37
Outstanding at September 30, 2020		6,649,882		$	7.00		9.40
Exercisable at September 30, 2020		783,236		$	1.64		8.40

Summary of Information about Stock Options Outstanding

The following table summarizes information about stock options outstanding at September 30, 2020 under the Plan:

	Options Outstanding						Options Exercisable
Range of Exercise Prices	Number Outstanding		Weighted Average Remaining Contractual Life (in years)		Weighted Average Exercise Price		Number Exercisable		Weighted Average Exercise Price
$0.31 - $1.02		253,931		7.43	$	0.98		162,037	$	0.96
$1.43 - $1.89		3,259,095		9.05		1.85		619,998		1.79
$12.85 - $19.00		3,136,856		9.92		12.86		1,201		12.85
		6,649,882						783,236

Schedule of Fair Value of Each Option Estimated on Date of Grant Using Weighted Average Assumptions

The fair value of each option was estimated on the date of grant using the weighted average assumptions in the table below:

	Nine months ended September 30,
	2020			2019
Expected volatility		115.09	%		91.60	%
Risk-free interest rate		0.42	%		1.88	%
Expected life (in years)		6.25			6.25
Expected dividend yield		—			—

Summary of Activity related to RSA Stock-Based Payment Awards

The following table summarizes activity related to RSA stock-based payment awards:

	Number of shares			Weighted-average grant date fair value
Unvested balance at January 1, 2020		1,335,349		$	1.42
Granted		432,301		$	3.26
Vested		(455,626	)	$	1.40
Unvested balance at September 30, 2020		1,312,024		$	2.03

Background - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2020	Dec. 31, 2019	Mar. 31, 2019
Subsidiary Sale Of Stock [Line Items]
Convertible preferred stock, shares outstanding	0	0
Common stock, shares authorized	500,000,000	500,000,000
Preferred stock, shares authorized	10,000,000	10,000,000
Common stock, par value	$ 0.0001	$ 0.0001
Preferred stock, par value	$ 0.0001	$ 0.0001
Common Stock
Subsidiary Sale Of Stock [Line Items]
Convertible preferred stock, shares outstanding				2,380,270
IPO
Subsidiary Sale Of Stock [Line Items]
Net proceeds from issuance of common stock		$ 166.6
Common stock, shares authorized	500,000,000	500,000,000
IPO \| Common Stock
Subsidiary Sale Of Stock [Line Items]
Number of shares issued and sold	9,573,750
Public offering price	$ 19.00	$ 19.00
Net proceeds from issuance of common stock	$ 166.6
Non-voting Common Stock
Subsidiary Sale Of Stock [Line Items]
Common stock, shares authorized	12,850,259	12,850,259	0
Common stock, par value	$ 0.0001	$ 0.0001	$ 0.0001

Risks and Liquidity - Additional Information (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Dec. 31, 2019
Risks And Liquidity [Line Items]
Accumulated deficit	$ (88,176)	$ (50,497)
IPO
Risks And Liquidity [Line Items]
Net proceeds from issuance of common stock	$ 166,600

Summary of Significant Accounting Policies - Additional Information (Details)	Sep. 18, 2020	Sep. 30, 2020
Summary of Significant Accounting Policies [Line Items]
Reverse stock split	0.8646
ASU 2018-13
Summary of Significant Accounting Policies [Line Items]
Change in accounting principle, ASU, adopted		true
Change in accounting principle, ASU, adoption date		Jan. 01, 2020
Change in accounting principle, ASU, immaterial effect		true

- Definition

Indicates (true false) whether accounting standards update was adopted.

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+ Details

Summary of Significant Accounting Policies - Schedule of Potentially Dilutive Securities Excluded from Computation of Diluted Weighted-average Shares of Common Stock Outstanding (Details) - shares	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	7,961,906	22,948,354
Series A Convertible Preferred Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share		11,736,119
Series B Convertible Preferred Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share		7,628,846
Unvested Restricted Stock Awards
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	1,312,024	1,394,056
Stock Options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share	6,649,882	2,189,333

Fair Value of Financial Instruments - Schedule of Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Quoted Prices in Active Markets for Identical Assets (Level 1) \| Money Market Funds
Fair Value Assets Measured on Recurring Basis Unobservable Input Reconciliation [Line Items]
Fair value measurement, recurring basis, assets	$ 233,364	$ 18,779

Accrued Expenses and Other Current Liabilities - Summary of Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Payables And Accruals [Abstract]
Compensation and related benefits	$ 2,099	$ 1,631
Research and development	3,763	658
Offering costs	220
Professional services and other	203	314
Accrued expenses and other current liabilities	$ 6,285	$ 2,603

Convertible Preferred Stock and Common Stock - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands		1 Months Ended		9 Months Ended
	Aug. 31, 2020	Sep. 30, 2020	Mar. 31, 2020	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Class of Stock [Line Items]
Proceeds from the issuance of common stock upon initial public offering, net of offering costs				$ 167,929
Common stock, shares authorized		500,000,000		500,000,000
Common Stock
Class of Stock [Line Items]
Common stock, voting rights				The holders of the voting common stock are entitled to one vote for each share of voting common stock held at all meetings of stockholders.
Common Stock \| Minimum
Class of Stock [Line Items]
Beneficial ownership percentage				9.99%
Common Stock \| Maximum
Class of Stock [Line Items]
Beneficial ownership percentage				19.99%
IPO
Class of Stock [Line Items]
Sale of common stock in initial public offering, net of offering costs of $2,538, (shares)		9,573,750
Proceeds from the issuance of common stock upon initial public offering, net of offering costs		$ 166,600
Convertible preferred stock converted into common stock		30,437,423		30,437,423
Common stock, shares authorized		500,000,000		500,000,000
IPO \| Common Stock
Class of Stock [Line Items]
Public offering price		$ 19.00		$ 19.00
Series C Convertible Preferred Stock
Class of Stock [Line Items]
Convertible preferred stock, shares issued	3,443,612	0		0		0
Convertible preferred stock, price per share	$ 14.5197
Net proceeds from issuance of preferred stock	$ 49,800			$ 49,826
Series B Convertible Preferred Stock
Class of Stock [Line Items]
Convertible preferred stock, shares issued		0	7,628,846	0		7,628,846
Net proceeds from issuance of preferred stock			$ 29,900	$ 29,942	$ 29,848
Non-voting Common Stock
Class of Stock [Line Items]
Common stock, shares authorized		12,850,259		12,850,259		0
Non-voting Common Stock \| IPO
Class of Stock [Line Items]
Convertible preferred stock converted into common stock		11,110,371		11,110,371

Stock-Based Compensation - Additional Information (Details) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020 USD ($) shares	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($) Plan $ / shares shares	Sep. 30, 2019 USD ($) $ / shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of equity incentive plans \| Plan			2
Aggregate intrinsic value of outstanding options	$ 153,700		$ 153,700
Aggregate intrinsic value of exercisable options	22,300		22,300
Stock-based compensation expense	1,472	$ 297	$ 2,461	$ 520
Stock Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted-average grant date fair value of options granted \| $ / shares			$ 8.44	$ 1.40
Aggregate intrinsic value of options exercised			$ 2,900
Stock-based compensation expense	1,200	200	1,900	$ 300
Total unrecognized compensation expense related to unvested stock option awards	39,100		$ 39,100
Total unrecognized compensation expense, weighted-average period			3 years 8 months 26 days
Restricted Stock Awards
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Award vesting period			4 years
Stock-based compensation expense	300	$ 100	$ 600	$ 300
Total unrecognized compensation expense, weighted-average period			2 years 11 months 8 days
Share-based payment arrangement, nonvested award, unrecognized expense	$ 2,400		$ 2,400
2020 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares authorized \| shares	4,680,000		4,680,000
Number of shares available for future grants \| shares	4,677,407		4,677,407
Terms of award			The number of shares of the Company’s common stock that may be issued pursuant to rights granted under the Plan shall automatically increase on January 1st of each year, commencing on January 1, 2021 and continuing for ten years, in an amount equal to five percent of the total number of shares of the Company’s common stock outstanding on December 31st of the preceding calendar year, subject to the discretion of the board of directors or compensation committee to determine a lesser number of shares shall be added for such year.
Award term			10 years
Percentage of shares outstanding used to calculate annual increase in number of shares that can be issued			5.00%
2020 Employee Stock Purchase Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares available for future grants \| shares	520,000		520,000
Shares issued \| shares			0
Maximum \| 2020 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Award vesting period			4 years
Minimum \| 2020 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Award vesting period			1 year
Vesting After One Year \| Restricted Stock Awards
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of stock options vested			25.00%
Vesting After One Year \| 2020 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of stock options vested			25.00%

Stock-Based Compensation - Schedule of Stock-Based Compensation Expense Recorded in Statements of Operations (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	$ 1,472	$ 297	$ 2,461	$ 520
Research and Development
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	630	135	1,047	250
General and Administrative
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	$ 842	$ 162	$ 1,414	$ 270

Stock-Based Compensation - Summary of Stock Option Activity (Details)	9 Months Ended	12 Months Ended
	Sep. 30, 2020 $ / shares shares	Dec. 31, 2019 $ / shares shares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Number of shares, Outstanding at January 1, 2020 \| shares	2,269,742
Number of shares, Granted \| shares	4,594,130
Number of shares, Exercised \| shares	(98,254)
Number of shares, Forfeited \| shares	(115,736)
Number of shares, Outstanding at September 30, 2020 \| shares	6,649,882	2,269,742
Number of shares, Exercisable at September 30, 2020 \| shares	783,236
Weighted average exercise price per share, Outstanding at January 1, 2020 \| $ / shares	$ 1.66
Weighted average exercise price per share, Granted \| $ / shares	9.38
Weighted average exercise price per share, Exercised \| $ / shares	0.98
Weighted average exercise price per share, Forfeited \| $ / shares	1.37
Weighted average exercise price per share, Outstanding at September 30, 2020 \| $ / shares	7.00	$ 1.66
Weighted average exercise price per share, Exercisable at September 30, 2020 \| $ / shares	$ 1.64
Weighted average remaining contractual term (years), Outstanding	9 years 4 months 24 days	9 years 2 months 12 days
Weighted average remaining contractual term (years), Exercisable	8 years 4 months 24 days

Stock-Based Compensation - Summary of Information about Stock Options Outstanding (Details)	9 Months Ended
	Sep. 30, 2020 $ / shares shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options Outstanding, Number \| shares	6,649,882
Options Exercisable, Number Exercisable \| shares	783,236
$0.31 - $1.02
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Range of Exercise Prices, Minimum	$ 0.31
Range of Exercise Prices, Maximum	$ 1.02
Options Outstanding, Number \| shares	253,931
Options Outstanding, Weighted Average Remaining Contractual Life (in years)	7 years 5 months 4 days
Options Outstanding, Weighted Average Exercise Price	$ 0.98
Options Exercisable, Number Exercisable \| shares	162,037
Options Exercisable, Weighted Average Exercise Price	$ 0.96
$1.43 - $1.89
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Range of Exercise Prices, Minimum	1.43
Range of Exercise Prices, Maximum	$ 1.89
Options Outstanding, Number \| shares	3,259,095
Options Outstanding, Weighted Average Remaining Contractual Life (in years)	9 years 18 days
Options Outstanding, Weighted Average Exercise Price	$ 1.85
Options Exercisable, Number Exercisable \| shares	619,998
Options Exercisable, Weighted Average Exercise Price	$ 1.79
$12.85 - $19.00
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Range of Exercise Prices, Minimum	12.85
Range of Exercise Prices, Maximum	$ 19.00
Options Outstanding, Number \| shares	3,136,856
Options Outstanding, Weighted Average Remaining Contractual Life (in years)	9 years 11 months 1 day
Options Outstanding, Weighted Average Exercise Price	$ 12.86
Options Exercisable, Number Exercisable \| shares	1,201
Options Exercisable, Weighted Average Exercise Price	$ 12.85

Stock-Based Compensation - Schedule of Fair Value of Each Option Estimated on Date of Grant Using Weighted Average Assumptions (Details) - Stock Options	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected volatility	115.09%	91.60%
Risk-free interest rate	0.42%	1.88%
Expected life (in years)	6 years 3 months	6 years 3 months

Stock-Based Compensation - Summary of Activity related to RSA Stock-Based Payment Awards (Details) - Restricted Stock Awards	9 Months Ended
	Sep. 30, 2020 $ / shares shares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Number of shares, Unvested balance at January 1, 2020 \| shares	1,335,349
Number of shares, Granted \| shares	432,301
Number of shares, Vested \| shares	(455,626)
Number of shares, Unvested balance at September 30, 2020 \| shares	1,312,024
Weighted-average grant date fair value, Unvested balance at January 1, 2020 \| $ / shares	$ 1.42
Weighted-average grant date fair value, Granted \| $ / shares	3.26
Weighted-average grant date fair value, Vested \| $ / shares	1.40
Weighted-average grant date fair value, Unvested balance at September 30, 2020 \| $ / shares	$ 2.03

Subsequent Events - Additional Information (Details) - Subsequent Event $ in Millions	Nov. 01, 2020 USD ($) ft²
Subsequent Event [Line Items]
Area of premises \| ft²	19,800
Second Amended and Restated Entrepreneur Client License Agreement
Subsequent Event [Line Items]
Area of premises \| ft²	8,800
Initial term of license	26 months
License agreement term description	Pursuant to the Amendment, the initial term of the License is twenty-six months commencing on November 1, 2020 and terminating on December 31, 2022 (the “Initial Term”).
License fee	$ 3.0
License renewal term	12 months
Description of license renewal option	The Company has an option to renew the License for twelve months commencing on January 1, 2023 at a monthly renewal license fee increased by 5.0% for a total of $1.4 million payable during the renewal term.
Percentage increase in monthly renewal license fee	5.0
Monthly renewal license fee payable	$ 1.4
Increase in monthly license fee upon exercise of ROFO	0.2
One-time payment made as consideration for ROFO	$ 0.2